Device for developing and fixing xerographic images



Nov. 29, 1960 w. LIMBERGER DEVICE FOR DEVELOPING AND FIXING XEROGRAPHIC IMAGES Filed April 12. 1957 2 Sheets-Sheet 1 wrm/ro@ MILTEAJ L/MBEAGK .L arl.

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Nov. 29, 1960 w. LIMBERGER DEVICE FOR DEVELOPING AND FIXING XEROGRAPHIC IM Filed April l2, 1957 2 Sheets-Sheet 2 United States Patent 2,961,993 DEVICE FOR DEVELOPING AND FIXING XEROGRAPHIC IMAGES Walter Limberger, Hamburg, Germany, assigner to LumoprintV Zindler KG., Hamburg. Germany Filed Apr. 12, 1957, Ser. No. 652,400 Claims priority, application Germany Apr. 16, 1956 i 10 claims. (ci. 11s- 537) .Mypresent invention relates to a device for manufac- Vturirlgcopies using xerographic layers as well as a method employing this device.

It is `known to prepare copies using xerographic layers located on a layer support. Before the preparation of a copy, the xerographic layer must be formed in an electrode arrangement. The xerographic layer is illuminated and covered with a powder containing pigment particles which adhere to the configuration of the latent electrostatic image of the master in the Xerographic layer. To produce the copy, the pigment particles are fused into the Xerographic layer.

The manufacture of copies using xerographic layers has considerable advantages, although the use of this method has not been previously possible on a large scale since the apparatus required is extremely complicated and since no readily operable device has been known to combine the several processes of the method. Even the distribution of the powder on the latent electrostatic image requires an exact and line determination of powder dispersal'which could not be carried out in known devices without a considerable consumption of the powder. The measuring of the amount of powder and the particular distribution of the powder could only be controlled heretofore with difficulty and upon distribution the powder led to substantial soiling of the whole apparatus.

The invention has the object of providing a readily operable device which makes possible the preparation of copies with xerographc layers without material powder wastage and provides that in operation the special requirements of the particular images are taken into account.

According to the invention, a base plate is provided with a tensioning device in order to stretch the layer support on the base plate; and the area occupied by the layer support on the base plate is covered at a certain height above the layer support; at the same time devices are provided in order to guide the coating powder to the space between the layer support and the cover without removing the cover. The tensioning device is constructed as a frame and has a dish-like lower part to which a handle is secured. Over the dish-like lower part is located a tensioning rim for the layer support, which has a certain height and serves as a collecting rim for the powder grains on distributing the pigment particles on the latent electrostatic image.

In a preferred embodiment, the tensioning device is constructed in the form of a box with a closure device over the tensioning rim, so that the manufacture of copies is possible with ordinary illumination. ln particular, this closure device is constructed as a slide and is made transparent. On the closure device is located a preferably removable supply device for the powder, which is so arranged or constructed that no illumination of the electrostatic layer disposed in the box can occur through this opening. This opening serves at the same time for removal of the powder before fusing of the pigment particles.

In a particularly preferred embodiment of the invention, the base plate carrying the layer support serves as the electrode in connection with a forming device and if required as part of a heating device arranged in the tendevice. The base plate is electrically connectable to the forming device and may be constructed of copper, or as a foil.

In a further preferred embodiment, a supply container for the toner communicating through one or more openings with the inside of box-like tensioning device is arranged directly on the box-like tensioning device.

In using the device according to the invention, the manufacture of copies with xerographic layers is considerably facilitated, since the layer support need only be stretched in the tensioning device, which is subsequently moved into different cooperating processing devices provided with slots.

One of these devices is the forming device, which consists of an electrode arrangement. It is so constructed that over the tensioning device a number of electrodes having small radii of curvature (eg. waves) are arranged, whereas the counter-electrode is disposed under the tensioning device. The potential of this counter-electrode is supplied, on inserting the tensioning device into the slot of the forming device. In a preferred construction, the lower electrode is located at ground potential so that the charged plate is arranged within the tensioning device.

An illuminating device which is likewise provided with a slot into which the box-like tensioning device according to the invention is inserted, in order to expose the xerographic layer.

On these two elements, devices are provided which cooperate with special means provided on the closure device to ensure, for example, that the closure device of the tensioning device is opening on insertion into the forming and illuminating apparatus, and closed upon removing the tensioning device.

The forming and illuminating apparatus can be used with a plurality of tensioning devices according to the invention, since they are in use only for a short time for preparing a copy. The tensioning devices themselves serve for distributing the coating powder of the latent electrostatic image and in one embodiment also as a fusing device. By this, it is ensured that a particularly fine distribution of the coating powder on the electrostatic image will result, and that no movement of the electrostatic layer is required before fusing of the pigment particles.

Further `advantages and features of the invention will appear from the specification of the embodiments illustrated in the accompanying drawings. In the drawings:

Fig. l shows a section through a tensioning device of box-like form according to the invention;

Fig. 2 shows a plan view of this device;

Fig. 3 shows a diagrammatic `front view of the whole arrangement on a considerably reduced scale; and

Fig. 4 shows a front view of the device according to the invention.

From Figs. l, 2 and 4 can be Seen the construction of the device serving as the hand apparatus. At the edges of a lower dish-like part 1, the plate 2 of a heat-conducting electrical conductor is arranged. The plate 2 preferably consists of copper. In order to give it only a small heat capacity, it is constructed in a preferred em bodiment as a foil which is firmly stretched on the rim of the dish 1.

Within the dish l and under the plate 2, the heating coil 3 is arranged, which runs over the whole surface of the device. The current supply for the heating coil 3 is provided by an insulator connection 4 at the side on which the handle 5 with the electric supply is arranged.

Under the dish 1 is located a frame 6 with the same dimension as the edge parts of the dish 1. The frame 6 is pivotally mounted upon the dish-like lower part 1 by a hinge 7 so that it can be tilted upwards. At the side which faces that having the hinge, a closure device '8 is arranged which is preferably constructed as a catch and engages in a cavity in the edge part of the frame 6. The closure device 8 is preferably located on the side of the device on which the handle is arranged so'that operation is possible with the thumb of the hand holding the handle 5.

This dish-like lower part 1 and, if required, the frame part 6 consist of a heat-resistant material which at the same time has little weight. For example, these parts are preferably manufactured of an asbestos product.

The edge parts of the frame 6 have on the lower edge facing the plate 2 anundercut 9 which is so dimensioned closure device, in the form of a slide member 10, transg I parent to red light. This slide member slides for example in guides 11 provided on the side of the frame 6. On the side of the device carrying the handle 5, a filling funnel 12 for the powder is provided which leads to a channel 13 which is so curved that no direct illumination can occur through this inlet opening. For example, the channel 13 can have a helical shape. The funnel is so arranged on the slide 10 that the channel opens into one corner of the frame 6. This arrangement enables the removal of excess powder without opening the device by shaking the excess powder into this corner and then inverting it and allowing it to run out from the channel 13 and the funnel 12.

The projection 15 containing the funnel 12 is releasably constructed in a particular embodiment, wherein at the same time the outlet opening in the slide 10 is arranged for receiving a closure catch. The projection 15 also has a spherical depression 16, 17 on each end face, which facilitate use of the projection 15 as a handle for moving the closure device 10. For the same purpose, on c the other side of the device an abutment 18 is provided which co-operates with a corresponding abutment for example on the forming device or illuminating device and which automatically opens the frame 6 on sliding the device into this apparatus. For example, a restoring spring can be arranged between the slide 10 and another part of the device, for example the handle 5, so that the device automatically closes on removal of the forming or illuminating device. If such a power store is not provided, it is sulicient for removal of the device to exert a pressure on the projection 15, particularly the cavity 14, in order to return this slide to the position shown in Fig. 1.

It can be seen from Fig. 3 that a current supply lead 19 is connected to the handle 5 of the device. At its free end, the current lead 19 has a three-prong plug 20 over one of which the necessary current for the heating coil 3 and the others the potential of the electrodes located in the forming device below the apparatus are led to the plate 2. In the preferred construction, this serves as a measuring device which is connected to ground.

Switch devices for controlling the current supply are located on the handle 5. For example, the press button switch 21 is provided by means of which a short heat pulse can be produced. Because of the low heat capacity of the plate 2, it is suicient to switch on for only a few seconds in order to heat the xerographic layer to about 120 C. Within the scope of the invention is the construction of the switch 21 as a time switch which automatically switches oi after a predetermined time nterval. This time interval can be made dependent upon the layer support used and the image characteristics in the manufacture of several copies from one master.

What I claim is:

bottom plate forming side walls and a cover plate spacedly held on said frame above said bottom plate, said frame being provided with internal fastening means for removably mounting said carrier sheet on said bottom plate in said box, said box preventing light rays capable of objectionably affecting said xerographic layer from reaching said sheet, said frame and said coverplate being movable away from said bottom plate for opening said box to enable insertion of said carriersheet, shielded inlet means on said box above said bottom plate enabling the introduction Yof developing powder into the space above said bottom plate while barring the entrance of said light rays, and heating means below said bottom plate for fusing said powder onto said xerographic layer.

2. A device according to claim l wherein said frame is 0hingedly secured to said bottom plate and adapted to be tilted upwardly thereon, said fastening means including a recessed formation on the underside of said frame. 3. A device according to claim l wherein said cover plate consists of a material transmissive to red light rays only. i

4 A device according to claim 1, further comprising a handle on said box for moving the latter in a manner distributing said powder over said xerographic layer.

5.A device according to claim 1 wherein said inlet means comprises a funnel-shaped extension projecting outwardly from said box, said extension being provided with a tortuous channel.

6. A device according to claim 5 wherein said cover plate is slidable on said frame, said extension being provided on said cover plate and forming aknob thereon facilitating its displacement.

7. A device according to claim 1 wherein said bottom plate is electrically conductive.

8. A device according to claim 7 wherein said bottom plate is a metal foil.

9. A device for developing and fixing a latent image on a xerographic layer of a carrier sheet, comprisinga substantially closed box, said box including a bottom plate of good thermal conductivity, a frame above said bottom plate forming side walls and a cover plate spacedly held on said frame above said bottom plate, said frame being provided with internal fastening means for removably mounting said carrier sheet on said bottom plate in said box, said cover plate being removably mounted on said frame for opening said box to enable insertion of said carrier sheet, said cover plate consisting of a material transmissive to red light rays only, said box preventing other light rays from reaching said xerographic layer, shielded inlet means on said box above said bottom plate enabling the introduction of developing powder into the space above said bottom plate while i barring the entrance of said other light rays, heating 1. A device for developing and fixing a latent image means below said bottom plate for fusing said powder onto said xerographic layer, and a handle on said box for moving the latter in a manner distributing said pow?v der over said xerographic layer.

10. A device according to claim 9 wherein said cover plate is slidably held in said frame, further comprising abutment means on said cover plate for displacing the latter from its operative position upon contact with an external stop.

References Cited in the le of this patent UNITED STATES PATENTS 2,550,724 Sabel et al May 1, 1951 2,586,484 Sabel et al Feb. 19, 1952. 2,600,580 Sabel et al June'17,j1952 2,689,179 Walkup et al Sept, 14, 1954' 2,750,922 Walkup et al June 19, 1956 2,791,949 Simmons et al. May 14, 1957 2,826,168 Grant Mar. ll, 1958` 2,831,409 Bixby et al Apr.` 22, 1958 2,894,486 Matthews July 14, 1959` 2,910,351 Szpak et al Oct. 27, 1959, 

